1 files changed, 100 insertions, 0 deletions
diff --git a/Lib/test/test_asyncio/test_locks.py b/Lib/test/test_asyncio/test_locks.py
index 3c94baa..1eb25e7 100644
--- a/Lib/test/test_asyncio/test_locks.py
+++ b/Lib/test/test_asyncio/test_locks.py
@@ -5,6 +5,7 @@ from unittest import mock
 import re
 
 import asyncio
+import collections
 
 STR_RGX_REPR = (
     r'^<(?P<class>.*?) object at (?P<address>.*?)'
@@ -774,6 +775,9 @@ class SemaphoreTests(unittest.IsolatedAsyncioTestCase):
         self.assertTrue('waiters' not in repr(sem))
         self.assertTrue(RGX_REPR.match(repr(sem)))
 
+        if sem._waiters is None:
+            sem._waiters = collections.deque()
+
         sem._waiters.append(mock.Mock())
         self.assertTrue('waiters:1' in repr(sem))
         self.assertTrue(RGX_REPR.match(repr(sem)))
@@ -843,6 +847,7 @@ class SemaphoreTests(unittest.IsolatedAsyncioTestCase):
         self.assertEqual(2, sem._value)
 
         await asyncio.sleep(0)
+        await asyncio.sleep(0)
         self.assertEqual(0, sem._value)
         self.assertEqual(3, len(result))
         self.assertTrue(sem.locked())
@@ -885,6 +890,7 @@ class SemaphoreTests(unittest.IsolatedAsyncioTestCase):
         sem.release()
 
         await asyncio.sleep(0)
+        await asyncio.sleep(0)
         num_done = sum(t.done() for t in [t3, t4])
         self.assertEqual(num_done, 1)
         self.assertTrue(t3.done())
@@ -904,9 +910,32 @@ class SemaphoreTests(unittest.IsolatedAsyncioTestCase):
         t1.cancel()
         sem.release()
         await asyncio.sleep(0)
+        await asyncio.sleep(0)
         self.assertTrue(sem.locked())
         self.assertTrue(t2.done())
 
+    async def test_acquire_no_hang(self):
+
+        sem = asyncio.Semaphore(1)
+
+        async def c1():
+            async with sem:
+                await asyncio.sleep(0)
+            t2.cancel()
+
+        async def c2():
+            async with sem:
+                self.assertFalse(True)
+
+        t1 = asyncio.create_task(c1())
+        t2 = asyncio.create_task(c2())
+
+        r1, r2 = await asyncio.gather(t1, t2, return_exceptions=True)
+        self.assertTrue(r1 is None)
+        self.assertTrue(isinstance(r2, asyncio.CancelledError))
+
+        await asyncio.wait_for(sem.acquire(), timeout=1.0)
+
     def test_release_not_acquired(self):
         sem = asyncio.BoundedSemaphore()
 
@@ -945,6 +974,77 @@ class SemaphoreTests(unittest.IsolatedAsyncioTestCase):
             result
         )
 
+    async def test_acquire_fifo_order_2(self):
+        sem = asyncio.Semaphore(1)
+        result = []
+
+        async def c1(result):
+            await sem.acquire()
+            result.append(1)
+            return True
+
+        async def c2(result):
+            await sem.acquire()
+            result.append(2)
+            sem.release()
+            await sem.acquire()
+            result.append(4)
+            return True
+
+        async def c3(result):
+            await sem.acquire()
+            result.append(3)
+            return True
+
+        t1 = asyncio.create_task(c1(result))
+        t2 = asyncio.create_task(c2(result))
+        t3 = asyncio.create_task(c3(result))
+
+        await asyncio.sleep(0)
+
+        sem.release()
+        sem.release()
+
+        tasks = [t1, t2, t3]
+        await asyncio.gather(*tasks)
+        self.assertEqual([1, 2, 3, 4], result)
+
+    async def test_acquire_fifo_order_3(self):
+        sem = asyncio.Semaphore(0)
+        result = []
+
+        async def c1(result):
+            await sem.acquire()
+            result.append(1)
+            return True
+
+        async def c2(result):
+            await sem.acquire()
+            result.append(2)
+            return True
+
+        async def c3(result):
+            await sem.acquire()
+            result.append(3)
+            return True
+
+        t1 = asyncio.create_task(c1(result))
+        t2 = asyncio.create_task(c2(result))
+        t3 = asyncio.create_task(c3(result))
+
+        await asyncio.sleep(0)
+
+        t1.cancel()
+
+        await asyncio.sleep(0)
+
+        sem.release()
+        sem.release()
+
+        tasks = [t1, t2, t3]
+        await asyncio.gather(*tasks, return_exceptions=True)
+        self.assertEqual([2, 3], result)
+
 
 class BarrierTests(unittest.IsolatedAsyncioTestCase):